size = int(input("亲输入棋盘大小:"))
for i in range(size):
    for j in range(size):
        if i == 0 and j == 0:
            print("┏", end='')
        elif i == 0 and j == size - 1:
            print("┓", end='')
        elif i == size - 1 and j == 0:
            print("┗", end='')
        elif i == size - 1 and j == size - 1:
            print("┛", end='')
        elif j == 0:
            print("┠", end='')
        elif i == size - 1:
            print("┷", end='')
        elif j == size - 1:
            print("┨", end='')
        elif i == 0:
            print("┯", end='')
        else:
            print("┼", end='')
    print('')
